[Moore] Add the SimplifyProcedures pass.

[hailongSun2000]

Cause we intend to entirely inline the always_comb body into the module body(moore.module). Due to the difference way between continuous and blocking assignments, we decided to create a new pass named SimplifyProcedures to insert a local "shadow" variable in always blocks for every module-level/global variable that the process modifies. Quote @fabianschuiki 's example:

origin:

module Foo;
  int a;
  int x, y, z;
  always_comb begin
    a = 1;
    x = a;
    a += 1;
    y = a;
    a += 1;
    z = a;
  end
endmodule

after performing SimplifyProcedures pass:

module Foo;
  int a;
  int x, y, z;
  always_comb begin
    int local_a = a;
    local_a = 1; a = local_a;
    x = local_a;
    local_a += 1; a = local_a;
    y = local_a;
    local_a += 1; a = local_a;
    z = local_a;
  end
endmodule

[hailongSun2000]

Thanks for the code review in advance! ❤️

[fabianschuiki]

LGTM! Thanks for adding all the infrastructure for Moore dialect passes in this PR 👍